The unique Seekins Precision side port design minimizes recoil as well as muzzle rise. Instead of allowing the first port to do the majority of the work, their proprietary front facing ports spread out the load minimizing felt recoil and reducing muzzle flash. Instead of using a crush washer, a knurled jam nut is included to make installation and removal a breeze. No special gunsmithing is required. The Seekins Precision ATC brake is designed to be used on barrels with a diameter at the muzzle of no more than .750". Most standard AR-15 barrels are .730-.750 diameter at the muzzle unless it is a heavier than normal barrel contour or a bull barrel. This is so that the jam nut can overlap the barrel. The rear of the compensator is .855" diameter and can be mounted with a crush washer if desired.